Ensure Solution.js can run in Node

Currently a number of tests are not run in node because of how `Blob` and `File` objects are utilized. This also means that the entire library can not be used in Node, which blocks the creation of an api that executes the Solution deployment process... which is a long-term goal of the Hub Team.

That said, rest-js and hub.js leverage patterns and external libraries to handle `Blob`'s

Hub.js pulls in `fetch-blob` and abstracts out blob in a `_which-blob` helper as shown here:
https://github.com/Esri/hub.js/blob/master/packages/common/src/resources/_which-blob/_which-blob.ts

We will need to look for a similar option for `File` - there is `file-api`, but it's not clear if that is designed for isomorphic libraries or not.